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The life history of the Ling cod Ophiodon Elongatus Girard Wilby, George Van 1924

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THE LIFE HISTORY OF THE LING COD OPHIODON ELONGATUS GIRARE by George Van Wilby THE LIFE HISTORY OF THE LING COD OPHIODON ELONGATUS GIRARE by George Van Wilby A Thesis submitted for the Degree of MASTER OP ARTS i n t h e DEPARTMENT OF ZOOLOGY. THE UNIVERSITY OF BRITISH COLUMBIA AfRlL, 1924 . r .^ 1 OPHIODON ELONGATUS,GiiRARD. FOREWORD. After a consideration of several Biological problems for research, the v/orking out of the life-history of Ophlodon elongatus was decided upon because of its economic importance and because comparatively little work has been done towards the critical study of its habits, habitat, grovrth rate, age, food, enem.ies, etc. This is due partly to the fact that the distribution is limited to the West Coast of i'Jorth America from Alaska to California, and more particularly to the atraitj; of Georgia and the Halibut banks west of Prince Kupert B.C.; partly to the fact that so little has been done on other more important problems concerning Pacific marine fauna that the attention of investigators has been turned elsewhere; and that this particular aspect of the problem, v/hich is emphasized masi Sti*ongly, namely the determination of the relationship of the age and length by means of the scales, is a comparatively new field of study. Very great assistance in accomplishing the objective of examining ^uu specimens, of the ^±ng Cod was given by,the manage raent and employees of the wholesale fish markets in Vancouver, Special mention must be made of the courtesy extended on all occasions by the Crov«i Fish Company.whose market has been open at all times for the examination and measurement of the ijing Cod in stock. Very valuable assistance has been given by tiie manager, Mr. Ives, and his employees regarding the habits, dis-tribution, capture and sale of the Ling Cod, Great assistance was also given by the Haig Fishing Co., the Royal Fishing Co., II. the Canadian Fishing Co., and the Ocean Fisheries l^ td. Two very serious drawbacks presented themselves at the beginning of this study as all the fish, with only a few excep-^ -^  tioBS, v/ere brought in from the fishing grounds decapitated and dressed for sale. However a factor was worked out for the lengtii of each fish with its hea.d in place so that the remaining dif-ficulty which has remained unsolved was the determination of the sexes, a problem which ca.nnot be cleared up very v;ell by examining a i.ing,Cod with its viscera removed. That part of the problem v^hich req.uired the most time anc. the greatest care v/as the examination of the scales. A large part of the laboratory work consisted in mere routine, soaking, cleaning and sorting the scales before examination could be at-tempted as the slime must be entirely removed from each scale before the light and dark bands corresponding to the summer and v/inter growth are clearly visible. The four main divisions of this study are: (1 ;, An anatomical description of Ophiodon Blongatus. (2). A discussion of the life-history, food, paras-ites, distribution, capture, market, etc, (3). A brief history of scalegttidy« the practical a'nplication of the laiowledge, gained from the life of other fish, to the problem of the life-history of the Ling Cod. (4;, Conclusions. * Throughout the whole period of this research I have been greatly assisted by Prof. G. Mclean Fraser who has been very helpful with his advice on all difficulties which have arisen i l l from t i n e t o tir-.e '^s the worh •oTorves^eCi. I am a l s o indebted t o liim for t h e use of lii? OVTI " Ich t} i70io~ica i i io tes" to \7liich r e f -erence i s •:ade in t":c t e x t . IV. i/OiM'i'Eiii'a, Foreword I Contents Iv . Anatomical Description « Life History t> Foods b Parasites b Distribution 9 «iear 9 Economic Data 1u iiistory of bcalestudy 11: Method of Examination i4 Explanation of I'ables 16 Explanation of Uxirve lO OonoXusions 19 Bibliography 'd.\ Age-iength Table Age-length uurve iilaT OF Ii^ LUbl'RAl'IOl^ b. Frontispiece. Ophiodon eiongatua, crirard. View of viscera. Face page 7. Jfhotographs of i>calea. Face page ifa. Oi'KIODOi^ ! ELOEGATUS, Girard. (LKG COD). Ophiodon was described by Girard in the Fjroceedings of the Academy of natural Sciences, rhiladelphia in lb^4, page 153 as "elongatus". In the same publication he again refers to Ophiodon as Oploporaa. (1856, page 135). In this sedond descrip-tion he recognises that the two are really the same. The spec-ific name, I'AaTHERIIIA, is also synonymous v/ith Si^ OiJGATUb, Jordan and Evermann, (l), describe the genus Ophiodon as f ollov;s: "Body elongate, low, little compressed. Head long, rather pointed, its surface ecaleless. Mouth terminal, very large, Jaws with very strong, sharp, unequal teeth, some of them csai-ine-like; long series of cardiform teeth on vomer and palatines Gill openings very" wide, the membranes not ujiited, free from the isthmus. ;:'reopercle vvith a fev; biuntlsh spines; a dermal flap over the eye. Scales very s:nall, becoming smooth \7ith age. Lateral line single, continuous. Dorsal fin long, deeply notch-ed, the spines about 24 in number, slender and flexible, tiie middle ones highest; anal fin long, v/itho\it distinct spines; ventrals'1,5 , inserted somev/hat behind pectorals; pectoral fin broad; pyloric caeca very numerous; gill rahers tubercle-li'ce. Species of large size; am.ong the largest of the cottiformfish-es; used as food; the flesh livid blue or green in color, (iUtf , snake; orfauV » tooth.) Ophiodon elon^atus, c-irard, is -veil supplied v.dth-comnon and trade names being fcior.n. as Cultus God, Buffalo Cod, i-in^ : Cod, Blue God, u-reen Cod and "bte?.::ier" Cod. "lie first tv:o are more historical than the others; lin^ God is undoubtedly the most cor;".on; Blue and 'jreen Cod are referred to because of the color of the shin and the flesh; the name Steamer Cod merely being a trade name amongst the fishermen referring to the mode of shipment from the halibut banhs. Belonging to the family hezagrammidae, ( the '^ resnlings }, because its dorsal fins are connected; its anal fin being verj^  long, %7ith rays 2u or more, the anal fin ?/-ithout spines; the Ling Cod belongs to the ^ub-Pamily Ophiodontinae which has but s single genus, Ophiodon, and a single species, elongatus, The distinguishing featiires of the genus Ophiodon being: The gill membranes not connected; the mouth large, the jaws armed v;ith strong canines; a lateral j-ine on each side; scales ctenoid; preopercle armed. Jordan and 3vermann, (2;, in their description of the species elongatus. state;that; "Head 3t; depth 5. J^. X:CL,2^-, A. 22. head large, the snout sharp, conic, nouth very large, the lower jav; prominent; maxil-lary reaching beyond orbit; each jaw with a series of large pointed teeth bent inward and immovable; front of upper jaw v/itn 2 to 4 larger canines;outside of the series of large teeth each jaw has numerous small, sharp teeth;vomer and palatines v;it3 a single rov^  of canines;supraorbital tentacle much shorter than • pupil; dorsal fin beginning above preoperole, the fin very deep-ly nothiied, the highest spines nearly 1/3 length of head; cauda± emarginate. Dark "brovm ahove, much mottled; dorsal fin and whole up-^ er part of body covered with small rusty brown spots of varying size and hue; lower parts of the body of a livid bluish green, especially in the adult, the flesh and all mem-: branes tinged, \vith green; ground color often bluish or reddish tinged; yoitng sometimes bright green; fins duslcy, mottled, the dorsal and caudal v/ith a very narrov;, pale edging. Length 4u inches. Pacific coast of America, aitka to banta Barbara; very abundant, reaching a v/eight of yj to 4u pounds, being one of the most important food fishes on the coast, (elongatus, elon-gate. )" Ophiodon elongatus begins life as one of many hundreds of eggs laid in an op-acLue, v/hite, gelatinous mass by the female aroxmd the weeds on a rocky bottom or in a crevice on the side of a rock just beneath the low tide line more or less out of reach of the ever-present starfish, (I'ycnopodia), nudibranchs, crabs and other bottom-loving enemies, The female is knov.Ti to spawn as much as a third of her ovm weight, an eighteen pound fish producing as much as six poiuids of eggs. About 170,000. Throughout the complete period of incubation, lasting from about the latter part of January to the middle of end of ilarch, the male Ling Cod keeps constant watch over the opaque v/hite mass of eggs until they all have hatched out. jy^YiP-^ this weary vigil, unaccompanied by the female, the male Ophiodon is ever on the alert as there are numerous enemies ready at the least opportunity to devoxu:' the eggs. He attacks them ferociously with his v/ell-armed mouth which is capable ofa very serinus woimd with its well-developed, conical teeth and exj-tremely muscular jaws. At length the eggs, which are about 'd/^ mm. in diameter and so opaque that little derelopraent can he seen from without until the eye appears just before hatching, produce the alerin v/hich is about 11 to 11d mm, in length and very well developed. This early development is q.uite necessary when one considers how many enemies must be guarded against and evaded during the life-cycle of the Ling Cod. Dr. C. McLean Fraser, (3). has been as able as anyone, perhaps better able than most, to observe the early stages aftei hatching. His description follows: "Although I have not got these earliest stages, I have beer fortunate enough to get some embryos just hatched out. V/hen the eyes are developed they show as dark spots in the eggs. After development had proceeded thus far I examined the eggs at inter-vals and thus managed to get a number hatched out shortly after they were brought into the laboratory. This was on Alarch 25th. The nev/ly-hatched embryo or alevin as it may nov; be called, is 11-12 ram, in length, with development vrell advanced. A certain amount of color is produced by a number of fine dark spots on the head, bands of them on each side of the dorsal fin and a less pronounced band belov/ the lateral line. There is no break in the continuity of the median fin except at the anal opening, but there is little, of it anterior to that opening. The pectoral fins are present, but they are not v/ell developed. They do ftot seem to be used at all to assist respiration. There is no sign of the ventral fins i "There is not much sign of skeletal tissues. A broad plate - ^ of cartilage extends for some distance under the cerehrura, hut it soon narrows and disappears before the optic chiasma is reached. At the sn.terior end of the notochord it appears again, forming an irregular plate of considerable size, A portion of it extends out to form part of the capsule.of the ear and poste eriorly it grows up aro^ 'ond each side of the medulla almost to the mid-dorsal line, but this lasts only for a short distance. -Laterally it connects up with the articular portion of the man-dible, which is slightly developed. There is a cartilaginous rod in each gill arch. The skeleton of the pectoral girdle is but slightly developed, and this is only in the part some dis-tance from the middle line, in the fin itself. The notochord is relatively rather small, and a.t this period is entirely vacuo-lated, "The nervous system is v/ell developed. In the brain the cerebral hemispheres are almost distinct; the optic lobes are large, with the'cavity separating as it passes back\';ard;the epiphysis and the pineal body show up well; the hypophysis and the saccus vasculosus are relatively of large size, and the cra:^  nial nerves shovj distinctly. Judging from their appearance, the sense organs must be almost as well suited for action as they are in the adult. The nasal pits are q.uite deep and possess a large sensory surface, the eye has the structural characteris-tics and the herve supply of the adult, while the ear is rela-tively of large size, and is extensively chambered with th^ ampullae showing distinctly, "Although much of the yolk— there is an oil globule presen — remains unabsorbed, the digestive system is apparently of 6^  high enough development to look after food taxen directly from tlie sea. At any rate in certain other fishes there is not so high a development when the yolk is all absorbed. The mouth is of large size, with the posterior portion of the cavity in dir-ect connection with the outside through the large gill-clefts. The digestive tube does not vary much in size throughout, but is bent back on itself to form a loop of considerable length. The anal opening is qv.ite far forward, a short distance poster-ior to the yolk-sac. The lobed liver is of large size with well developed hepatic tissue. The pancreas shows up distinctly. "The excretory organs must be strongly functional, as the kidneys have got much beyond the single tubule stage and the ducts are relatively of large size, "jn the circulatory system, the heart has become q.uite mus-cular, with the eharabers and general shape much the same as in the adult. The aorta with its branches through the gill arches can be traced easily, and many other of the large arteries and veins have become distinct. "Taking it as a whole the young Ophiodon, as it emerges from the egg, is in good condition to look softer itself, althou>^ h as in the. majority of young fishes, it will have enemies in plenty, enough to require the use of all its pov/ers, no matter how fully they are developed," For the first few years of its life the young alevin rapid-ly grows larger and larger, living along the rocky shores IK and amongst the kelp and eel-grass. During this time the flesh of the young Ophiodon is a distinct green color. This color appears to be a dye as it is transferred to halibut when the View of "Viscera. iiiote the extremely elongated m.uscalar stomach, well adapted for containing large quantities of food, ^he S-Light swelling at the lower edge of the photograph is caused by the small Perch,half-digested, which v/as used for bait. In cases where a large meal is being digested, the stom.ach is capable of great expansion. As is shov/n by the above view, the mou-^ h practically joins the stomach, there being practically no dif-ferentiation into gullet and stomach. irlsh are piled together in the-market places. From a lov/-tide line feeder the yoimg x.ing Cod of from six to tv/enty-three inches gradually goes deeper and deeper until it reaches 5 to lu fathoms. As the greater depths are attained the green color in the flesh gradually disappears and the typlc al Blue Cod form is assumed. From this depth dovm to ahout' luu fathoms the length is about 3u to 4^ inches v;ith an occasional specimen measuring u^ inches and weighing 45 to u^ pounds. The largest loiovm by the local fishermen weighed 83 pounds in the "round", iiost of the vety large fish are brought from the ric-inity of I'ender Harbor and tiuathiaski Cove. Throughout the life history of Ophiodon we find a constant struggle, he either being preyed upon, or, as is more frecLuent-ly the case, preying upon other denizens of the deep, not even disdaining to swallow members of his own species. To fishermen the liing God is loiov-Ti as a voracious eater, lie is carnivorous and herbivorous to some extent. It is no uncommon sight, when the setlines are hauled up, to find that one i^ ing Cod has sv;al-lowed the bait and another, perhaps larger, has engulfed him, either totally, or as is frequently the case, partially, leav-ing a portion of the victim hanging out of the mouth. In connection v/ith this feature of the habits of the hing Cod one's attention is dravm to the fact that the well-develop-ed conical teeth are merely for seizing and holding the prey, there being no mastication done by the mouth. -^H may be seen from the accompanying photograph the stomach is extraordinarily large and sac-like, hence the holding, gorging and digesting of the victim are often carried on simultaneously. b , The foods utilized by the iiing Cod are (juite numerous, Clupea -fallasii, the Kerring; Gymagaster aggregatus , the small Jr'erch so common along the shores; Capelin, 3aiov/n as Smelts; Sar-dinia (Clupanodon j, the -filchard; various Crustacea such as Cancer sp.; iiacrura, Shrimps; Copepods; ^chizopods; etc., as well as numerous ground-feeders v/hich are associated because of their similar habits, siich as the iJculpins, and occasionally members of his ov/n species. In addition to the animal food in the stomachs of several of the fish examined, Zostra, or eei-grass is frequently found rolled up In little ba.lls about an inch in diameter, The digestion of the foods must be very rapid, judging from the fact that specimens brought dovm from -fender Harbor in fish-traps alive were caught at sundov.Ti and examined the next day at 9 a.m. The powerfully muscular stomach in each case bein^ almost empty except for the badly mangled vertebral bones of the Herring that had'been used for bait, and a few rolls of Zostra, The examination of the stomach contents was rather limited how-ever as most of the ling Cod were brought in from the grounds dressed and xvashed ready for market. Parasites are q.uite commonly found on the body of the Ling Cod as well as in the viscera and tis.'^ ues. Those actually observed were: Argulus pugettensis, Dana, On the anal fin. Lepeophtheirus pravipes , V/iison, In the mouth, « -Nematode sp, in the coel-omic cavity. rlanarian sp, similar to a liver flujce. In the brain cav-ity. (Mii That these are only some of ma.ny parasites seems aito-,r;;ether likely as the fishermen are very emphatic in their opin-ion that even the corape^ ratively ra,pid-moving ^Ing Cod are msu-ally foimd v/ith ssrveral different kinds of "lice", as they calJ the Copepods, upon them. As was descrihed by Evermann and Jordan, Ophiodon is found almost anywhere along the ivestern coast of America from Alaska to California. The two chief areas in British Columbia waters are the u-ulf of Georgia and the Hecate otraits. In the latter area the J-iing Cod are perhaps a secondary consideration as they are caught on the lines set for Halibut. Those dis-tricts which seem to be most valuable as fishing-groiinds in the ijulf of u-eorgia are I'ender H.arbor, Q,uathiaski Cove, Texada Is-land, the vicinity of i'^ anaimo and any other place where there is a rocky bottom. I Having studied the habits of the ling Cod for many years the fishermen have adopted almost exclusively the set-line form of fishing. In almost all cases they use Herring for bait, al-though -ferch and sometimes Smelts are used. In any case it is essential to have a small bait. The usual type of boat is the one Icnovm as the Columbia River gasboat. It is a stout 23 to 4u foot boat that is well able to withstand the sudden and violent stomms which are com-mon along the coast in the winter months and at the same time they are very easily handled as well as being capable of carry-ing very large shipments of fish for their tonnage. Each boat usually has several *^skates of gear" to look 1_u^^ af*er every day. This "skate" consists of a line 363 fathoms in length anchored at each end. At every fathom there is a smaller line ending in a baited hook. These smaller lines are called "gangings'.'-^ t end of each "skate" a flag is placed for ease in recovering the gear on the return trip. If the fishermen are operating from dories on the Haliout banks they freq."u.ently tie on 6 or 7 "skates" one after another in a long line where the fishing is very good. These dories are operated from the larger halibut boats and at times they may have as much as a mile of line out in a single place. An occasional Ling Cod is caught on a troll but this is not a very satisfactory method as the rocky nature of the fish-ing grounds practically prevents this form of capture. Several fishermen working in a small v/ay use handiines set OTit in a similar way to the men working on a larger scale. This method of fishing is used most frequently in very small areas, Within the last few years the Ling Cod fishing has passed largely into the hands of the Japanese fishermen v/ho have pros-pered so ?;ell that they have entered the wholesale and retail business as v/ell. A visit to the fish-markets of Vancouver shows the industrious foreigner doing as thriving a business as his long-established neighbors of Occidental origin. At the present time there is a ready sale for all the G-reen and small Blue Cod in the local market, which includes all of British Columbia, There is often some difficulty in disposing Locally of the larger 4u lb. Ling Cod which are coarser than the iroung fish and more difficult to handle in the restaurants, ho-tels, boats and trains where small orders are better filled by a -[U few small fish than by one or tvw larger ones. . There is already q^ uite a large trade with Sastena cities principally Calgary, Reglna, and as far East as Toronto, An oc-casional shipment is made to Montreal and i-Jew York-. These irreg-ular shipments are often caused "by a large order for Salmon, not g[uite filling a refrigerator car, being supplemented by a standing order to fill up the car with "heavy" fish, such as Ling God and Halibut, in order, to give some idea of the economic value of the ling Cod, it is placed immediately after the balmon and Halibut 9,8 a food fish. An enquiry as to the prices obtained in the mar-ket shawed a range of from 4c, to 15c, wholesale according to the season. In the month of liiarch immediately after the closed season, the highest prices are obtained, whereas during the sal-mon run the lowest prices are reached as the salmon are more de-sirable. Also the Cod-fishing is less rirecarious so that the supply at times eiccee'ds the demand. It is at this time that many of the Ling Cod are placed in cold storage or smoked and held un.til a more favorable price is obtainable. During the closed season there are very few Ling Cod sold fresh as the only fishing grounds open are on the Vi'est Coast of Vancouver Island. Since this area is exposed to the full sweep of the J^ 'acific Ocean the catches are small because of the many 3torm.s. The price charged there is 9c, which does not include 2c, for freight charges, so that the price is prohibitive and the, sale small at this time in the local market, The importance of the Ling Cod as a food fish is rapidly Increasing due partly to the rapidly decreasing numbers of the 12. Dalraon and Halibut, and partly to its ovm more widespread sale. As the numbers of the -Liing Cod are becoming depleted already, a more rigid enforcement of the fishing regulations must eventual ly be demanded. At present no fish is allov/ed for sale undeS 16 inches in length. This part of the regulations seems to be adhered to verj well, V/here the preservation of the u-enus Ophiodon would be aid-ed materially however is an extension of the closed season. As it is now the closed season for ling Cod is from the first of January to the first of laiarch. The logical extension would be to include the latter part of December at least as the females are carrying many hundreds of potential Ling Cod which are lost when they are caught. If for na other reason than that of food value, the extension of the closed season v/ould be justified as the parent fish are in rather poor condition for table use at spawning time. ?^  Agassiz, (4), in his classical memoirs on fossil fish laid the foundation for the modern work on fish scales, and it is well iQiovm that he based his classificatioii chiefly on their structure. Williamson, 15^, has published two papers on the scales of fish. He explained their mode of growth and brought forward the theory that the origin of the various types of scales is & derivation of the primitive denticles of Eiasmobranchs. , E.a. G-oodrich, (6;, in a paper, "On the acales of Fish, liiving and Extinct, and their importance in Classification", gums up his research as followa.' 13. "Further, it appears that the structure of.the scales is very uniforra v/ithin the families, and that closely allied fam-ilies usually have very similar scales. The cosmoid scale oc-* curs in the extinct Osteolepidoti tCrossopterygii; and Dipnoi; but in no other group of fish, bimilarly the ganoid scale oc-curs in the Teleostomi and never elsewhere, The paleoniscoid type is restricted to the Paleoniscidae and their immediate al-lies; while the lepidosteoid type is universal among the Proto-gpondyli, the Aetheospondylii, the Pholidophoridae, and not found in any other grpup as far as is Icnown. "These different kinds of scales then, are of great system-atic value, and the position of a fish in any of the large div-isions can at once be determined by an examination of its scale. Doubtless all the types have evolved from some ancestral scale, and numerous intermediate forms will be found, ?;hose position will be difficult to assign; but so far the chief types remain remarkably distiiict from each other." V/ithin the last few years much work has been done by -frof, T. D, A. Cockerell, who has advanced a system of identification of fishes by their scales. This research covering modern fishes for the most part. • Prof. G. McLean Fraser, (1), has applied this study of the scales to another problem, namely that of working out the life history of the Pacific balraon, especially the Goho, Oncor-hynchus kisutch, and the Herring, Clupea Pallasii. In these ^  cases the rates of growth have corresponded very well v/ith the ages of the fish as, Represented by the grov/th-rings on the scales. 14. In the case of Ophioclon eion.::ct-as , as can be seen fror. t'le acGonpan:'in£: photo£-raphs, there i? a distinct differentia-tion into li~ht ani^ . dar2: bands of -jrov.iih-rir.g's correspondiri;: to '-;ie s'jnr.:er and winter seasoias. Rapid £:rov.-tr. accoripan^ vin": tlie more plentiful food supply, slov/er growth v.'ith closer rin.^ s when food is scarce. In many cases there appeared abrasioris aion£: the edj^ es of the bands of rinses corresponding to the latter part of win-ter. As these marks, v/hich appear to be reabsorbed portions of the scale, seem to shov/ each year after the third, very defin-ately in many cases, so that there seems to be some significan-ce to their presence. In all probability they are spa\7nins-marks, but a definite decision carinot be made as yet because o^ the uncertainty as to the sex of the indiTiduals examined. iiince the majority of the fish examined v:ere brou^rht in to the local niariets decapitated and dressed, sex-determin-ation was out of the Question. 2his lack of a head however did not present a very great difficulty as from an ex8.::iinat}.on of a number of fisl: with their heads on, a factor vras foxind which proved to be alnost a constant. The variation being not more than 2'i^, and the average worked out to be that the head, from the lateral angle of the jav;s to the tip of the snout v.-as 3^"'-of the length of the bod;r from the lateral angle of the jaws to the caudal end of the spinal coliimn. hence a decapitated i^ iri^  Cod measuring 17 inches from the angle of the jaws to tl;e end 03 the spinal column v/ould be 25 inches, (17x1.,3b;, v*'ith its head in situ. It is on this basis that tlie table given herewith is 15. •compiled. After measuring the fish, in order to get a satisfactory set of scales from each ling Cod for comparison, the region posterior to the operculum betv/een the dorsal and pectoral fin was utilized as it is less liahle to injury and also the scales are comparatirely large at this area. It was usually necessary to scrape off a thick coating of slirae "before taking the sample then with a gentle scrape from the pectoral fin anteriori,y the scales came out rery easily. Each sample was then placed betweeii the leaves of a small pad and the length and date noted. Upon arrival at the laboratory, the most efficient method of treatment was found,after several attempts to Increase the manual preparation speed, to have a dozen numbered watch-glasseisi slightly filled vdth water in which to soak the scales before examination under the microscope. About two dozen scales were taken at a time and after soaking for about half aji hour the scales' without too serious abrasions were separated from the slime by rubbing between the fingers and thumb and placed in other watch-glasses. It was found also that if the rough sorting' ?/ere done for all sets at the same time that more speed in man-ipulation v;as attained. Of the normal scales 'lu were selected at random and the v/inter bands checked off by the aid of the camera lucida. In cases where there seemed to be Tincertainty as to the age of the fish under examination, other scales v/ere added to the origi-nai lu and the average number agEeeing was taken as representative. In some cases as many as luu scales were examined and only 2 or 3 had sufficiently well-developed central rings to be beales from ling God length 33.75 in. aho\7ing extrerae vari-ation in size, shape, canaliculi and ease in reading the winter checks. Age 1u years. x?. bth. 7 th. 6 th. 5 th. 4 th. 3rd. 1st. As ahove, lov;er left higher magnification. i^th. year ?th. x'-^y x9. iiength 3u .3 in. iNote variation in size, shape and legibility of scales. Also note differ-ent ways in which the aanaliculi radiate from the nucleus. These canal-iculi are characteristic of Ophiodon elongatus. All from the same specimeil.. Same as lower left aboTe, Magnification, x2^, This is to show winter checks more clearly. •9th. year. •8th. -7 th. )th. ith. ^th, .^ 3rd. -nd, st. IT t» TT II n ti IT II x^3. As may be seen here the janaliculi may or may not start from the-nucleus. her.^tli ?A.2!y in, 6 th . Pth. 4til . 3rd. 1 s t , ^ ^ x.yd, Lenrith '^4,25 i n . 6.th. year. 5tli, "-— 4tli. J rrl , ' - J J . C L , 1 •-••^  x t b . p^ft^I'^s^ >>•• w i n t e r check end of i s t , ye&ir, be a l e taicen from i-ing God l e n g t h ^-^In, Caught Aug. 2u, 1915. Winter check end of 1st, year, same fish as above. 3>rd. y e a r , i:;nd. y e a r . I S t . y e a r . readable. These fish were discarded as not being representative!. With these exceptions only, the first ^uu ijing God to be exam-ined are represented in the tables. iFrecLuentiy the scales required very carefux examination and in some cases the winter eheoJcs were indeterminate for one or two years. After examining the first ZKJ^I scales, (iiu fishy, it was found to be more desirable to measure from the nucleus to the side, rather than from the nucleus to the end of the scale where it fits in the pocket, as there are two sides to check one another whereas there is only one longitudinal direc-tion available. Thus if the check corresponding to one of the winter seasons did not appear on one side, it could be fotmd on the other and when traced arouad would fill the gap in most oases. 3uu iiing Uod were examined ranging in age from 3 to i ^  years as follows: aumber of i^ pecimens. -Age. 1 a 4 37 «u '3^ ; iu3 «3 31 15 b 3uu Total. From the above table it will be J5 ' * ^ 6 7 0 9 lu (1 \c *3 seen that tne greatest numbers are between the ages of b and i i years with the maxjjmMa at 8 years. This is accotmted for by the fact that thse repreo-ent the most desirable sizes for thd market as those fish wnicn are yotmger are too soft and those which are oider are too I I m 7^j coarae, ihe range in length corresponding to vneae ages being from lb in, to pa in, measured from tne tip of tne snout uo the end of tne spinax coiumn, xhe accompanying table snows the age at une top of eaoa column ajid the lengtn to the nearest cittarter inca in eacn hor-izontal row, ihe figTire at the intersection of the rows repre-senting the number of fisn examined. From this table also the degree of variaoion can be seen to reach its maximum at the age of 9 years, extending from 2>.o in, to jJiJ.V^  in,, or 7,> in. in a n . An^ jaough this seems to be a considerable range there are many factors oon-oertted which cause the variations. 'xhe widely scattered points from which the fiah are brought and the consequent difference in habitat and food-supply have a great influence on tne rate of growth, xhe lacJc of information as to zue sex is aiso a factor which must be considered, in order to show the amotmt of variation in eacn year the following table has been complied, xhe uiaximum variation of 7,> in, between the smallest and largest fish nine years of age seems to be very great but even here there is no overlapping ox more than d years at a time, conseauentiy the age can be estim-ated from the measurement of a fish to within a year. Age. iiength variation. Actual Variation. 5 4 6 I 9 1 4 . 14,-ii^ t o ( b , 1 ? . ^9*'l!> i d . 2 > 2 1 . 7 > i i u , 2 > dA,:?o ^ 2 , > u i i b ,>u •d9,2> ^i>» 4.^> 6. 1 1 B I ib. Age. i i 13 length Variation. 34.7> to P^.lt> 37.>u 4u.7> Actual Variation. 3.ii> 4. From the aoove table it can be seen that the greatest variation in length tor the same age coincides more or less with the lengths of fisfo which are most desirable for the looai marJcet, nameiy between iB in, and 3b in. This variation as has been mentioned ia probably due to the diversity of distribution habitats and food-supply. In addition to the above tables a curve has been plotted to show the average length for each year. This average was ar-rived at as follows, using the age of 4 years as an example. JLiength, i 4 . 2 > 1 3 . l b , 2 > 16.7 :? l b . ( liumber. i 3 d i 1 b / T o t a l , 1 4 . 2 > 4 > , 3ii.:? i6.73 iti. l > . b 1 'I'he average length for the 4 year old iiing Uod is i;?,oi inches. Instead of joining the points that.indicate the average for the different years, the points are simply put in place and a straight line has been drawn to show the variation from a direct ratio between age and length. The deviation from this straight line is very little in the case of the younger and older fish but is greater in those intermediate ages that cor-respond to the most suitable sizes for mariceting, iiJven here the variation is not so great considering that the catches examined are such a heterogeneous lot. When it is considered that these I •ti I Si 19. fish came from all parts of the ii^ raits of i^ eorgia and even as far north as the liecate c>-craits in more open waters it is not to he wondered at that there is some auch slighi, variation, Aa has been established definitely in the case of the Uoho oalmon there is a diatinct difference in xne rate of growth of the fish growing in the otraits of wreorgia and tnose which come from'the racific off the coast of Vancouver island. It would seem that in the case of the Jjing Uod that tnere is the same possibility and this would account in part for the deviation of the curve from one straight line. Uonciusionsi (.1 ), i'hat if a sufficient number of i«ing Uod were taken there would tend to be an even greater correlation between the age and length than has been shown. (2), I'hat if a distinction had been made between ' the sexes there might have been the same cor-relation between the age and length in two curves, the one parallel to the other, K3), That if a separate table could have been made for the age-i-length of the ^xng Ood from each fishing-ground there would have been a ciosei correlation, 14;, As a logical conclusion from the above, if thfe specimens had been tajcen in each case trom on j 9 lishing-ground instead of from such widely separated points as xender narbor, X'lanaimo, the west coast of Vancouver Island, and the necatj p. i I I 'I (>;. otraits, many of the deviations from the straight line would he rectified. i)'or, it cer-tainly seems reasonable that the difference in geographical distribution must entail a differ* ence in the chemical composition of the water, especially as regards salinity. Differences in temperature must also be effective in control-ling growth. Variations in depth at different points is another factor which must cause some effect on the grov/th. From the observations made it seems almost cer-tain that, if sufficient specimens of the xiing uod, of the same sex, from the same locality, from the same habitat, were taken at the same time of year, they would shaw a growth ctirve ii: direct proportion to their age. I I i if II d\ (1). (3;. {4;. (3). iHOTEb. Jordan and Svermann, Fishes of worth America, p. 1875. „ « IT II II .. .1 p . 1 8 7 5 . Fraser, Cm,, -fh.D, Ichthyologicai i^ otes on Ophiodon elongatus, rub, Biol. Board of Canada, 'i^ 'ib. p. I4, Agassiz, L, Recherches snr les Poissons Fossiies, i^ eu-chatel. 1 033-4-4. V/iiliamson, \'i .0. "On the iiicroscopic c^tructure of the Scales &c."-fhil. Trans, vol. cxl, , I'dAy. V/illiarason, V/.C. "Investigation Into the i^tructure and Development of the scales and Bones of Fishes." -fhil. Trans, vol. cxii., i33u. (These references are given hy u-oodrich, E.i., as ref-erences in his paper, "=506 (fc>;, belov;;, (ioodrloh, 3.S., F.R.s., F.Z.t>. , "On the ocaiea of Fish, living and Extinct, and their importance in Classifica-tion." froc. 2oo. t)oc., hond^on. 19u7, p. 73'. Fraser, C.n., i-'h.D. Ichthyological Jiiotes on The Diag-nosis of Fish "by means of their Dcales. Fub. liioi. Board of Canada. 1916. p. 17. i r .25 .5u .75 .25 .5u .75 1 ' . .25 .5U .75 1 7 . .25 .5u .75 19 . K -25 • ,75 rai. .25 .5'J .75 . ^25 r ,75 i 2 5 . .25 .5u .75 24. P. .25 * .50 .75 '^5. . I .25 .5u .25 .50 .75 27. .25 .50 28. .25 .50 .75 29. .25 .50 3 1 4 1 AGE-LEflGTH OF OPHIODOU ELOiiGATUS. 5 6 7 8 9 1u 11 ^^ 13 2 1 2 1 6 1 11 4 'd 3 1 2 16 17 32 2 5 2 7 6 12 4 25 2 11 3 2U 1 1 13 2 Ik! 3 5 1 4 1 3 1 5 12 4 1 1 12 4 \ • \ I'he graph shovm herewith ahows the average length of the -uing t^ od for each year rrom > oo »>• Aheae averages were arrived at as shown on page ib, ihe absoisaae represent the xen^th meastired from the tip of the buout to the end of the vertebrax ooxximn. xhe ordin." ates represent the age« Average xiength. Age. 3 4 b 7 0 iw 1 I 12 1 4 . i p . b l l b . 19 2 u , 1 o 22.>7 2;>.3b 29.3> 3 5 . > 3b . fab 3 9 . Jb 4 i i . 4 ^ I n . I I I I I I I I M (1 t i t l I I f l 


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